Bacteria go motoring

Bacteria take some gears for a spin, creating a challenging question: how …

Tuesday is science day in the New York Times, but I was a day late in reading it. Yesterday's issue has a number of interesting stories, but one of the short summaries seemed especially appropriate. Earlier in the week, I'd mentioned how nerve cells would preferentially grow along surfaces coated with a specific organic material. That behavior is hardly specific to nerve cells, though, as many cells—including those of single-celled organisms—will preferentially adhere to some surfaces.

A research group was studying a bacteria that normally adheres to and moves along the gills of fish. But fish gills aren't the most convenient substance to work with, so in previous work, they isolated strains that would adhere to and move along glass in order to better study the biochemical basis of these bacteria. But they didn't stop working with the species, named Mycoplasma mobile, when that work was done. Instead, they started channeling the bacteria into small silicon gears: once in place and stuck to the gear surface, the motion of the cells began to turn them. The work doesn't appear to be published yet, but the Times provides some video of the device in action. Those green glowing bits? Those are the bacteria.

One interesting thing about this work is that in the previous study, the research group showed that you don't even need a live cell to get this gliding behavior. If they punched a hole in the cell membrane and let all the contents out, the cell would come to a halt. But they could be restarted simply by adding a solution of the cell's normal fuel, ATP. This has the potential to vastly simplify the system, although it does eliminate a live cell's capacity for self-repair.